Hello @Michael Silverman,
Thank you for posting your query on Q & A forum.
As per your question, I understand that you have invited few users as guest users to your tenant and they are not visible in the Users Blade in Entra ID.
How is the user invited to the tenant (through Azure/Sharepoint/teams)?
If the user has become a guest user through an invitation shared through sharepoint/teams, the user would not show up in Entra ID users as there are chances that the guest account is not completely created/provisioned.
Please try to re-invite the user from Entra Portal and ask the end user to complete the invitation sign up process to successfully show in the Entra ID Users.
If this answers your query, do click Accept Answer and Yes for was this answer helpful. And, if you have any other queries, please feel free to comment on this.